A case study of the rainfall during the passage of Typhoon 7002 over the Kii Peninsula is made on the assumption that the rainfall R(x, y, t) at each station (x, y) should be interpreted as k(x, y)×f(x, y, t), where f(x, y, t) is the rainfall which would be caused at the station by the traverse of a disturbance if there were no orographic effect and k(x, y) is the amplification factor of the rainfall which would be dependent upon the topographic features around the station and the direction and strength of prevailing wind. The results of analysis show that the distribution of h(x, y, t) whish is roughly proportional to f(x, y, t) and its behavior have a good correspondence to the distribution of moving radar echoes, while the distribution of R (x, y, t) is considerably controlled by topographic features over the peninsula. Examples of the pattern of k(x, y) and f(x, y, t) over the peninsula are presented.
Experimentally the collection efficiency of snow crystals by snow crystal sondes was determined to be 36%. This value was smaller than that calculated from Langmuir and Blodgetts' chart, assuming a ribbon shape for the collecting body. However, since the value determined experimentally was considered to be more practical, it was adopted in the measurement of snow crystals in clouds. Sometimes cloud droplets were collected by the snow crystal sonde in snow clouds, and they showed a reasonable size distribution insofar as cloud droplets with diameters greater than 20μ were concerned.
The vertical structure of snow clouds was observed at Otaru, Hokkaido in the winter of 1970, utilizing snow crystal sondes. The following results were obtained. 1. The vertical distribution of snow crystal shape agreed well with that expected from Nakaya's Ta-s diagram. This agreement shows that the snow crystals fell, as they were, without any effect of strong updraft at side of the clouds. 2. Snow clouds of various grades of glaciation were observed: namely the early stage where the concentration of snow crystals is very small, the mature stage where the solid water content is comparable with the liquid water content, and the decaying stage where no cloud droplets were observed. 3. The growth rate of falling snow crystals was measured by the use of vertical distribution of diameter of the largest snow crystals at each level. The growth rate of snow crystals near the cloud top (in the initial stage of snow crystals) roughly coincided with those experimentally measured or theoretically calculated, however the growth rate in the middle or the lower layer of clouds (in the later stage of snow crystals) was much smaller than that near the cloud top. The small growth rate in the lower layer was considered to be because of the lack of cloud droplets in the layer. 4. The concentration of snow crystals was two or three orders greater than that of ice nuclei, even when the summit temperature of the clouds was considered. It was considered that the rapid freezing phenomena other than the riming phenomenon was related to the multiplication of ice nuclei.
The electric charge and size of drizzle drops were measured in-cloud along the Saddle Road between Mauna Loa and Mauna Kea on the island of Hawaii. A newly developed instrument optically detects the size of drizzle drops from 120μ to 700μ in diameter. The minimum detectable drop charge, as measured by the induction method, is 1×10-5e.s.u. In warm clouds, 11% of the drizzle drops were charged more than 10-5e.s.u., and 90% of the electrified drizzle drops were charged negatively. In thunderclouds, 70% of the drizzle drops were charged more than 10-4 e.s.u. and 60% of the electrified drizzle drops were charged positively.
Meteorological observations were carried out at two places in mountainous regions in the midwinter and snow-melting seasons of 1971 and 72; each place was represented by two nearby stations, higher and lower, having an altitude difference of 250 m. The following two facts were found : firstly, there were differences in sensible heat flux between the two stations under temperature inversion; secondly, the intensity of inversion was much greater in the midwinter season than in the snow-melting season.